Narrative:

I took off from hto in marginal conditions for VFR flight to teb. Checked weather repeatedly as day went by. Plan was to cross to the connecticut coastline and follow it VFR back to the new york metro area; as there are numerous airports in the event of a sudden change in conditions; and the route circumnavigates class B airspace. Airports gon; hvn and bdr all were VFR; with ceilings between 1;800 and 2;000 MSL; with all these fields at sea level. Since entering the middle ring of the new york class B abeam lga requires flight altitude of 1;500 or below; I normally do this trip at around 2;000 ft MSL anyway. [I] checked whether on computer at stop on way to airport. All the connecticut airports; as well as teb and lga; were VFR. All the long island airports west of us were VFR. There was light rain falling where it was VFR; but no other issues. We arrived at hto perhaps 10 minutes after checking the weather; and after what seemed like quick use of restrooms and change of clothes; we loaded the plane and taxied to the runway. Did run-up and took off; and we shortly found ourselves in complete IMC at a much lower altitude than what our final look at the weather had indicated. Hto was supposed to be marginal. It was not; at least to the northwest; and as the on board weather came up on the weather screen; every field on the southern shore of connecticut had gone virtually instantly from VFR to low IFR. We called boston center; asked for an IFR direct to an airport with VFR conditions; and were sent to hfd; then handed off to providence approach for the flight. Eventually we were able to descend to a safe MSA where conditions were VFR; at around 1;200 ft south of the hartford area; and landed VFR at hfd. The gap in the system here is that the weather was changing so fast that virtually no information was reliable.

Related reports:

Google
 

Original NASA ASRS Text

Title: C182 pilot departs HTO under VFR and expects to remain VFR to TEB. IMC is encountered shortly after takeoff and ATC assistance is required to divert to an airport with VMC.

Narrative: I took off from HTO in marginal conditions for VFR flight to TEB. Checked weather repeatedly as day went by. Plan was to cross to the Connecticut coastline and follow it VFR back to the New York metro area; as there are numerous airports in the event of a sudden change in conditions; and the route circumnavigates Class B airspace. Airports GON; HVN and BDR all were VFR; with ceilings between 1;800 and 2;000 MSL; with all these fields at sea level. Since entering the middle ring of the New York Class B abeam LGA requires flight altitude of 1;500 or below; I normally do this trip at around 2;000 FT MSL anyway. [I] checked whether on computer at stop on way to airport. All the Connecticut airports; as well as TEB and LGA; were VFR. All the Long Island airports west of us were VFR. There was light rain falling where it was VFR; but no other issues. We arrived at HTO perhaps 10 minutes after checking the weather; and after what seemed like quick use of restrooms and change of clothes; we loaded the plane and taxied to the runway. Did run-up and took off; and we shortly found ourselves in complete IMC at a much lower altitude than what our final look at the weather had indicated. HTO was supposed to be marginal. It was not; at least to the northwest; and as the on board weather came up on the weather screen; every field on the southern shore of Connecticut had gone virtually instantly from VFR to low IFR. We called Boston Center; asked for an IFR direct to an airport with VFR conditions; and were sent to HFD; then handed off to Providence Approach for the flight. Eventually we were able to descend to a safe MSA where conditions were VFR; at around 1;200 FT south of the Hartford area; and landed VFR at HFD. The gap in the system here is that the weather was changing so fast that virtually no information was reliable.

Data retrieved from NASA's ASRS site as of April 2012 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.